Electrochemical gene detection

K. Hashimoto, K. Ito and Y. Ishimori, Novel DNA sensor for electrochemical gene detection, Anal. Chim. Acta, 286 (1994) 219-224. 

Takenaka, S. Pseudo-polyferrocene coating of double stranded DNA with ferrocenylnaphthalene diimide and its application for electrochemical gene detection. Polym. J. 2004, 36, 503-512. 

Synthesis of ferrocenyl deoxyribonucleic acids (DNAs) and their application to electrochemical gene detection 06Y208. 

When a metal complex is formed with the nucleic acid base of single-stranded DNA (ssDNA), such ssDNA can be used as an alternative electrochemically-active DNA-binding ligand. For example, Palecek and coworkers reported the formation of a reversible redox-active metal complex by the reaction of osmium tetraoxide-pyridine with the thymine (T) base of ssDNA, and they developed an electrochemical gene detection method based on this modified oligonucleotide as a DNA probe [3]. 

Wang et al [24] first reported a DNA hybridization detection method based on the precipitation of silver on Au-NP tags and subsequent electrochemical stripping detection of the dissolved silver. The assay employed a sandwich-like protocol with streptavidin-Au-NPs labeling the biotinylated-breast cancer gene (BRCAl) sequences. 

In another approach to electrochemical DNA detection, metal complexes conjugated with DNA-binding ligands such as intercalators can be used for that purpose instead of electrochemically-active DNA probes. A gene-detecting method is known that is based on electrochemically-active metal complexes that show preference for dsDNA [16, 21-24, 29, 32—43]. The principle of this technique is shown in Fig. 9.3. 

Another method is explored with gene expression-based biosensors [19] for Cd measurement. A Cd-responsive promoter from E. coli is fused to a promoterless lacZ gene and monitored with an electrochemical assay of /J-galac-tosidase activity. The expected detection limit is about 0.1 mg L 1 with a response of a few minutes. As for stripping voltammetry, no real tests have been carried out for wastewater. However, biosensors can be considered as a promising technique for wastewater monitoring. 

Currently, a large spectrum of microbial biosensors have been developed that enable the monitoring of pollutants by measuring light, fluorescence, colour or electric current and electrochemical signal [60]. A recent study [19] shows that whole-cell biosensors based on the detection of changes in gene... 

The electrochemical DNA sensor shows impressive sensitivity and selectivity. The detection limit, estimated to be 5 pM, is competitive with previously reported HCMV DNA hybridization assays based on an enzyme label.52 Introduction of a noncomplementary DNA sequence (human ETS2 DNA gene) records an electrochemical signal consistent with background noise. The electrochemical DNA sensor is therefore selective for the HCMV DNA sequence. 

M. Aitichou, R. Henkens, A.M. Sultana, R.G. Ulrich and M.S. Ibrahim, Detection of Staphylococcus aureus enterotoxin A and B genes with PCR-EIA and a hand-held electrochemical sensor, Mol. Cell. Probes, 18 (2004) 373-377. 

ELECTROCHEMICAL DETECTION OF THE HYBRIDIZATION OF DNA STRAND RELATED TO BRCA1 BREAST CANCER GENE USING A TWO STRANDS ASSAY FORMAT... 

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